Myocardial infarction, commonly known as a heart attack, occurs when coronary artery obstruction cuts off the blood supply to part of the heart. The resulting lack of oxygen causes irreversible tissue damage (necrosis and apoptosis), due to the inability of the heart to sufficiently activate endogenous regeneration programs and self-repair. Such tissue damage is a leading cause of congestive heart failure, a condition in which the heart is no longer capable of effectively pumping blood. In the United States, there are more than a million heart attacks every year, and nearly 5 million people are afflicted with congestive heart failure.
There are no effective treatments for regenerating damaged cardiac tissue. Current therapies for congestive heart failure focus on preventing arrhythmia, progression of arteriosclerosis and recurrent myocardial infarction, but do not address the underlying tissue damage. More than half of patients diagnosed with congestive heart failure die within five years of diagnosis.
Stem cell therapy is a potential new strategy for cardiac repair. In the laboratory, it is possible to generate cardiac muscle cells from stem cells. This suggests that stems cells could be used to repair damaged tissue such as cardiac tissue in a patient; however, no therapeutic treatments based on such an approach are presently available. One difficulty that has been encountered in stem cell therapy is that of targeting sufficient numbers of stem cells to the damaged tissue to result in clinically significant repair.
There is, thus, a need in the art for methods for repairing or regenerating damaged tissues, including cardiac tissue, and for improving the targeting of cells such as stem cells to facilitate tissue repair. The present invention fulfills these needs, and provides other related advantages.